A wheel-supporting rolling bearing unit that supports a wheel of an automobile or the like rotatably with respect to a suspension device includes: an inner member having plural lines of raceway surfaces on an outer circumferential surface thereof; an outer member having plural lines of raceway surfaces on an inner circumferential surface thereof; and plural rolling elements disposed between the raceway surfaces of the inner member and the raceway surfaces of the outer member so as to be rotatable. Then, the inner member is supported rotatably to the outer member via the rolling of the rolling elements. Moreover, a flange for attaching the wheel thereto is provided on the outer circumferential surface of the inner member, and in addition, a flange for attaching the suspension device thereto is provided on an outer circumferential surface of the outer member.
In such a conventional wheel-supporting rolling bearing unit as described above, the inner member includes a hub ring having one raceway surface among the plural lines of raceway surfaces and an inner ring having other raceway surface. With regard to the hub ring and the inner ring, a cylindrical portion formed on an axial end portion of the hub ring is inserted through the inner ring, a die is pressed against a tip end portion of the cylindrical portion, which protrudes to an axial end portion side more than the inner ring, swing caulking is performed therefor, and an axial end surface of the inner ring is held by a caulked portion formed by caulking and expanding the tip end portion of the cylindrical portion radially outward. Hence, the hub ring and the inner ring are fixed integrally with each other to form the inner member. The swing caulking as described above can be performed by a swing forging machine (for example, as disclosed in Patent Literature 1).